1. Field of the Invention
This invention relates to a drill device or tool with an electromagnetic base, and more particularly to a drill device with an electromagnetic base in which swarf is difficult to cling to the cutter (annular cutter, drill or the like) mounted on the front end of the drill device.
2. Description of the Related Art
Conventionally, there has been proposed a drill device with an electromagnetic base having an electromagnet for attaching the drill device on a to-be-worked object (or workpiece) and a feed motor for automatically feeding the drill device towards the object. For example, the inventors of this invention invented a drill device with an electromagnetic base in which the rotation speed of the feeding motor for feeding the drill towards the object is lowered to lower the feeding speed when the load of the drill motor for rotating the drill is large and the rotation speed of the feeding motor is increased to increase the feeding speed when the load of the drill motor is small and filed an application (Application No. 540,197) at the U.S. PTO on June 19, 1990.
Thus, the operation of drilling the object can be efficiently effected without applying a heavy load on the drill or the object by controlling the load condition of the drill device or the feed speed according to the cutting condition.
That is, in the drill device with an electromagnetic base, the feed speed is controlled according to the magnitude of the load in the cutting operation so that the drill or annular cutter will be less subject to damage.
However, in a case where a thick object is drilled, it becomes difficult to remove swarf and therefore a heavy load tends to be applied to the drill or annular cutter. Therefore, some measures must be taken to easily remove the swarf.